       Iterate through a list

• To: mathgroup at smc.vnet.net
• Subject: [mg76886] Iterate through a list
• From: "Nick Hoffman" <hoffmannick at gmail.com>
• Date: Tue, 29 May 2007 05:02:03 -0400 (EDT)

```Hello! I'm (somewhat) new to Mathematica and I  need help to iterating
through a list and counting the occurrence of a number.

My list looks like:

{{1,0},{1,1},{2,x+x^2+x^4},{2,1+x+x^2+x^4},{4,x+x^2},{4,1+x+x^2},{4,x+x^4},{4,1+x+x^4},{4,x^2+x^4},{4,1+x^2+x^4},{4,x^3+x^4},{4,1+x^3+x^4},{4,x+x^2+x^3+x^4},{4,1+x+x^2+x^3+x^4},{5,x+x^3},{5,1+x+x^3},{5,x^2+x^3},{5,1+x^2+x^3},{5,x+x^3+x^4},{5,1+x+x^3+x^4},{5,x^2+x^3+x^4},{5,1+x^2+x^3+x^4},{8,x},{8,x^2},{8,x^3},{8,x^4},{8,1+x},{8,1+x^2},{8,1+x^3},{8,x+x^2+x^3},{8,1+x+x^2+x^3},{8,1+x^4}}

The number that I would need to keep track of is the first in each sub-
list.

So for the first couple {{1,0},{1,1},{2,x+x^2+x^4},{2,1+x+x^2+x^4},{4,x
+x^2},........

I would need to keep track of 1,1,2,2,4........

It will not always be 1,2,4,5,8's.  The numbers may be completely
different on each pass.  Each sublist may be composed of more items
but the number that I need to keep track of will always be the 1st in
the sub-list.  Any help or suggestions that you can give me will be
greatly appreciated.  Thanks so much!

```

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